Physical Sciences and Mathematics Commons^™

The Impacts Of Tilled-In Biodegradable Plastic Mulch On Soil Microbial Communities, Corissa L. Martin

Masters Theses

Plastics mulch films are used in agriculture to help increase crop production by regulating soil water retention and soil temperature while also preventing weed growth. Despite these benefits, plastic mulches have led to higher levels of microplastic pollution as weathering occurs. In response to this issue, biodegradable plastic mulches (BDMs) have been introduced to help reduce plastic pollution as they are designed to be tilled into soil after each growing season to continue degradation. Degradation of these mulch films is dependent on climate and, in some areas, complete degradation can take years. Since some biodegradable plastic mulches are made of …

Carbon Metabolism In Cave Subaerial Biofilms, Victoria E. Frazier

Masters Theses

Subaerial biofilms (SABs) grow at the interface between the atmosphere and rock surfaces in terrestrial and subterranean environments around the world. Multi-colored SABs colonizing relatively dry and nutrient-limited cave surfaces are known to contain microbes putatively involved in chemolithoautotrophic processes using inorganic carbon like carbon dioxide (CO₂) or methane (CH₄). However, the importance of CO₂ and CH₄ to SAB biomass production has not been quantified, the environmental conditions influencing biomass production and diversity have not been thoroughly evaluated, and stable carbon and nitrogen isotope compositions have yet to be determined from epigenic cave SABs. …

Evaluation Of The Symbiotic Relation Between Endophyte And Poplar Trees Exposed To Landfill Leachate, Catalina Vega Hurtado

Masters Theses

“The contamination of soil and groundwater from leachate leakage from landfill has turned, nowadays, into a global public issue. One of the main concerns about this pollutant is the potential threat to human and ecosystem health. The current research studied endophyte bacteria in association with poplar trees (Populus sp.), as a method of bioremediation of landfill leachates. The objective of the project was to identify treatment strategies that may improve plant performance (survival rates, plant fitness, and degradation efficacy) with the purpose of being implemented in phytoremediation plots, aimed to intercept and treat landfill leachate, before the contamination of watershed. …

Impacts Of Plant-Microbe Interactions On Seedling Performance In A Riparian Forest Invaded By Lonicera Maackii, Taylor E. K. Strehl

Masters Theses

Soil microbes have profound impacts on plant growth and survival and can either promote or inhibit plant dominance. Exotic plants are often strongly invasive because they have escaped their natural enemies, potentially including antagonistic soil microbes. I examined how the invasive shrub Lonicera maackii and a common native tree, Acer negundo, responded to soil microbial communities to determine the role of soil microbes in regulating invasion success. This was done by growing both species with microbes from invaded (L. maackii) and uninvaded (A. negundo) soils collected from three locations within a riparian forest. Seedlings were …

Microbial Extracellular Enzymes In Marine Sediments: Methods Development And Potential Activities In The Baltic Sea Deep Biosphere, Jenna Marie Schmidt

Masters Theses

The deep biosphere is defined as the subsurface ecosystem in which little energy is available to microorganisms and microorganisms can live for thousands of years. Heterotrophic microbes survive in the deep biosphere even though organic matter is limited and highly recalcitrant in nature. Measuring microbial extracellular enzyme activity provides a potential means to evaluate the rate at which microorganisms are performing carbon remineralization in the energy limited sediment beneath the seafloor. Extracellular enzymes breakdown organic compounds so that the nutrients can move inside the cell and be used for energy. This study explored the role extracellular enzymes play in the …

Rare Occurrences Of Free-Living Bacteria Belonging To Sedimenticola From Subtidal Seagrass Beds Associated With The Lucinid Clam, Stewartia Floridana, Aaron M. Goemann

Masters Theses

Lucinid clams and their sulfur-oxidizing endosymbionts comprise two compartments of a three-stage, biogeochemical relationship among the clams, seagrasses, and microbial communities in marine sediments. A population of the lucinid clam, Stewartia floridana, was sampled from a subtidal seagrass bed at Bokeelia Island Seaport in Florida to test the hypotheses: (1) S. floridana, like other lucinids, are more abundant in seagrass beds than bare sediments; (2) S. floridana gill microbiomes are dominated by one bacterial operational taxonomic unit (OTU) at a sequence similarity threshold level of 97% (a common cutoff for species level taxonomy) from 16S rRNA genes; …

Dissolution, Ocean Acidification And Biotic Extinctions Prior To The Cretaceous/Paleogene (K/Pg) Boundary In The Tropical Pacific, Serena Dameron

Masters Theses

The several million years preceding the Cretaceous/Paleogene (K/Pg) boundary has been the focus of many studies. Changes in ocean circulation and sea level, extinctions, and major volcanic events have all been documented for this interval. Important research questions these changes raise include the climate dynamics during the warm, but not hot, time after the decay of the Late Cretaceous greenhouse interval and the stability of ecosystems prior to the mass extinctions at the end-Cretaceous.

I document several biotic perturbations as well as changes in ocean circulation during the Maastrichtian stage of the latest Cretaceous that question whether the biosphere was …

Ph Dependent Antibiotic Resistance Of An Alkaliphilic, Halotolerant Bacterium Isolated From Soap Lake, Washington, Tiffany Charlynn Edwards

Masters Theses

"Soap Lake, located in Washington State, is a meromictic, soda lake. Many bacterial isolates retrieved from Soap Lake have been noted to possess resistance to multiple antibiotics. A likely explanation for the wide range of antibacterial resistance exhibited by these strains is due to the impact of high alkalinity on the antibiotics themselves and not due to the presence of antibiotic resistance genes. The aim of our study was to determine if select antibiotics are effective against Halomonas eurialkalitoleranis, a bacterium capable of growth over a wide range of neutral to alkaline pH values, to investigate the influence of alkalinity …

Effects Of Treated Wastewater Effluent On Microbial Community Structure In A Natural Receiving Aquatic System, Matthew D. Hladilek

Masters Theses

Despite our dependency on treatment facilities to condition wastewater for eventual release to the environment, our knowledge regarding the effects of treated water on the local watershed is extremely limited. Responses of these lotic systems to the treated wastewater effluent have been traditionally investigated by examining the benthic macroinvertebrate assemblages and community structure; however, these studies do not address the microbial diversity of the water systems. In the present study, planktonic and benthic bacterial community structure were examined at fourteen sites (from 60 m upstream to 12,100 m downstream) and at two time points along an aquatic system receiving treated …

Non-Thermal Plasma Inactivation Of Bacillus Amyloliquefaciens Spores, Yaohua Huang

Masters Theses

Bacterial spores have remarkable resistance to a variety of harsh conditions, causing spoilage in food industry and becoming the primary bacterial agent in biowarfare and bioterrorism. In this study, inactivation mechanisms of Bacillus amyloliquefaciens (BA) spores by non-thermal plasma (NTP) were investigated by using Fourier-transform infrared spectroscopy (FTIR) as a major tool to exam spores after NTP treatment. Chemometric techniques, such as multivariate classification models based on soft independent modeling of Class Analogy (SIMCA) and Principal Component Analysis (PCA), were employed to identify functional group changes in FTIR spectra. The IR absorbance bands correlated to dipicolinic acid (DPA) decreased after …

Analysis Of The Charleston, Illinois Water Supply For The Presence Of Organic Mutagens Utilizing The Ames Salmonella/Microsome Assay, Steven Lee Washburn

Masters Theses

Water samples from the Charleston, Illinois water supply and selected agricultural run-off areas were tested for the presence of organic mutagenic chemicals. The Ames Salmonella/microsome mutagenicity assay utilizing strains TA98 and TA100 was used to analyze concentrated water samples. A special set of samples was exposed to the S9 activation system coupled with the TA98 strain to simulate the mammalian metabolic system.

No mutagens were detected in any of the samples tested. Several positive and negative control systems were included in the testing system. Negative control systems were used to determine the average spontaneous reversion rates for each strain for …

Raw Water Quality In The New Charleston, Illinois Pump Storage Reservoir, Kevin G. Lookis

Masters Theses

Charleston, Illinois, a city located in east-central Illinois, recently implemented a new concept in a raw water system. Due to storage capacity-sedimentation problems in the old Lake Charleston-Embarras River raw water supply, the Charleston Pump Storage Reservoir was constructed. The new system involved building a dike separating the Lake Charleston impoundment from the Embarras River. Water to increase the storage capacity of the reservoir can now be selectively pumped into the impoundment from the river.

Raw water quality in the reservoir was monitored on a weekly basis for a full year from August, 1981 to August, 1982. The levels of …

A Statistical Approach To The Study Of The Ecosystems Of Seven Ponds In East-Central Illinois, Gregory Lee Orr

Masters Theses

Gross primary productivity, heterotrophic bacterial numbers, and net phytoplankton densities of seven ponds in Coles County, Illinois, were studied in relation to physical, chemical, and biological habitat variables (light intensity and duration, turbidity, water temperature, pH, dissolved oxygen, sulfur, nitrogen, phosphorus, production, bacteria, and phytoplankton). Ten observations were made for each pond (except where otherwise noted) from 17 June through 25 August 1974. Stepwise multiple linear regression analyses of the data were used in order to determine those environmental factors which were important in predicting (i.e., significantly correlated with) bacterial and phytoplankton densities, and production. A multiple linear regression equation …

Pesticide Effects In A Simulated Soil Ecosystem, Raymond J. Samp

Masters Theses

The screening of pesticides to determine which were most inhibitory to bacteria was accomplished by testing the effects of 10 pesticides on 9 different organisms using the disk assay method. Results showed that Gram positive bacteria were more sensitive to all pesticides tested than were the Gram negative bacteria. In addition, the hormone herbicides were found to be the most inhibitory to these bacteria and 2,4-D (2,4-dichlorophenoxyacetic acid), a hormone herbicide, was chosen for subsequent in vivo studies.

A soil perfusion apparatus was used to determine the effects of 2,4-D in a typical soil ecosystem. Bacterial plate counts and nutrient …